Question

from experience, you know that commercial jets typically fly around 500 miles per hour at a height of 30,000 feet. however, as you watch one fly high overhead, it seems to slowly pass by. what monocular depth cue best explains this?
texture gradient
motion parallax
linear perspective
overlap

Explanation:

Motion parallax is a monocular depth cue where objects that are closer seem to move faster than objects that are farther away. Since the commercial jet is at a great height (far - away), it seems to move slowly despite its high actual speed. Texture gradient is about the change in texture density with distance, linear perspective involves parallel lines converging at a vanishing point, and overlap is about one object covering another. None of these explain the slow - appearing motion of the distant jet as well as motion parallax.

Answer:

motion parallax